Re: [PATCH 0/2] KVM: x86/mmu: Plug an unsync shadow page leak

[Sean Christopherson]

On Fri, 05 Jun 2026 10:46:09 -0700, Sean Christopherson wrote:
> Recursively zap orphaned nested TDP shadow pages on emulated writes, not just
> when the parent is being fully zapped, to plug an unsync shadow page leak if
> the L1 hypervisor zaps bottom-up instead of top-down, as KVM's TDP MMU has
> done since commit 8ca983631f3c ("KVM: x86/mmu: Zap invalidated TDP MMU roots
> at 4KiB granularity").
> 
> Gory details in patch 1.  Patch 2 adds a stat that, very thankfully, we more
> or less have in our internal kernels, and without which, diagnosing the bug
> would have been much more difficult.
> 
> [...]

Applied patch 1 to kvm-x86 mmu.  I'll send a v2 for the stat, targeted at 7.3
(I want to give folks more time to weigh in on adding a new stat).

[1/2] KVM: x86/mmu: Recursively zap orphaned nested TDP shadow pages on emulated writes
      https://github.com/kvm-x86/linux/commit/69397c92de77

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